In the application of plaster and the like to a vertical substrate, it is common in the art to place a metal lath against the substrate prior to applying any plaster. The lath is secured to the substrate, as by nailing, and acts to help stabilize the plaster while it is in its flowable state prior to drying and tends to reinforce the plaster.
FIG. 1 shows a typical prior art metal lath which is essentially a screen made up of individual undulating strands secured to each other in a heel-to-toe arrangement similar to overlapping shingles. One disadvantage of such a known metal lath is that, while the openings of the metal lath generally allow plaster to be passed therein to make direct contact with the underlying substrate, the lath generally remains in close contact with the underlying substrate and very little plaster becomes positioned between the lath structure and the underlying substrate. To ensure that at least a minimum amount of plaster is positioned between the metal lath and the substrate, it has been known in the art to first secure vertical furring strips of thin wood to the substrate prior to mounting the metal lath. This places the metal lath a selected small distance away from the substrate and ensures that plaster is forced between the metal lath and the substrate when the plaster is applied with a trowel. Of course, in many instances it would be desirable, if possible, to eliminate the need for first nailing furring strips to the substrate to prepare it for receiving a lath.
Another problem presented by the use of known metal laths in plaster is that the plaster is essentially alkaline and tends to corrode or attack the metal lath. The resulting corrosion of the metal lath can leach through the plaster causing stains in the exterior of the plaster, can reduce the mechanical strength of the lath itself, and can reduce the mechanical bond between the lath and the surrounding plaster. Also, known metal laths, such as that shown in FIG. 1, typically have a directional bias, that is, they are more well-suited for receiving plaster when applied with a trowel moving in one direction than with a trowel moving in some other direction. Obviously, it would be preferred that a lath be equally well-suited to receiving plaster when applied with a trowel moving in any direction.
Accordingly, it can be seen that a need yet remains for a lath for securing plaster to a substrate which allows plaster to be filled in between the lath and the substrate, while not requiring the use of furring strips nailed to the substrate, which is substantially chemically inert in the presence of the alkaline plaster, and which is well-suited for receiving plaster applied with a trowel moving in various directions. It is to the provision of such a lath that the present invention is primarily directed.